Motion planning method of bipedal walking using partial-circular feet imitating wheel motion

In this paper, we propose a basic motion planning method for a bipedal walking which has both surmountability and energy saving performance. The proposed method is to use legs with partial-circular feet imitating motion of a virtual wheel. The partial-circular foot which has an arc bottom is handled as a part of the virtual wheel. By the method, the center of mass of the robot is kept to move horizontally at a constant velocity without collision with ground vertically, and the energy loss due to the collision can be avoided. We also present a design method of the radius of the partial-circular foot to realize stable motion against the errors of posture caused by reaction of swing leg and other disturbances. The effect by the proposed method is compared with that by a basic dynamic walking based on linear inverted pendulum model through physical simulator. As the result, the proposed method can achieve stable walking with 51% energy consumption of that by the dynamic walking. Additionally, it is known that the stability is higher and the energy efficiency is lower, when the radius of partial-circular foot is bigger.